plot_power: Plot power and fpr curve
In xyomics/bugpower: Generate power calculation report for microbiome data

plot_power plots the power and fpr curve for common and rare species or pathways.

1	plot_power(power.obj, target_power = 0.9, target_fpr = 0.05, title = "")

`power.obj`	A data frame generated by `calc_power` or `calc_power_common_rare`
`target_power`	The least power the study wants to reach. A number in (0,1). Default is 0.9.
`target_fpr`	The highest fpr of the study. A number in (0,1). Default is 0.05.
`title`	title for the plot. Default is "".